Effects of SiC interphase on the mechanical and ablation properties of C/C-ZrC-ZrB2-SiC composites prepared by precursor infiltration and pyrolysis

Carbon/Carbon (C/C) composites modified with ZrC-ZrB2-SiC particles were prepared by precursor infiltration and pyrolysis (PIP) process. Effects of SiC interphase on the mechanical and ablation properties of C/C-ZrCZrB2-SiC composites were investigated. The SiC interphase was deposited through low pressure chemical vapor infiltration (LPCVI). It was found that as the SiC interphase was introduced into the modified C/C composites, the flexural strength increased by 24% and the failure mode showed brittle fracture. The mechanisms for the strengthening of the modified C/C composites with SiC interphase were identified as (I) the deposition of SiC interphase in short-cut webs that strengthened the bonding between fibers and matrix promoting to stress transfer, and (II) the production of weak bonding between fiber bundles and matrix in non-woven webs improved the utilization of carbon fiber strength. SiC interphase increased adhesion between the ablation products and matrix, it could enhance the ablation resistance of the modified C/C composites in short term under the action of the evaporation. However, the long-time ablation resistance was reduced since the ceramic particles could not be incorporated into the composites during preparation due to the existence of SiC interphase. (C) 2017 Elsevier Ltd. All rights reserved.